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DRUG INTERACTIONS Drug Interactions
Local Anesthetics: Administration of DepoDur three minutes after a 3-mL test-dose (lidocaine 1.5% and epinephrine 1:200,000) increases peak serum concentrations of morphine (See CLINICAL PHARMACOLOGY). Increasing the interval between the test dose and DepoDur administration to at least 15 minutes minimizes this pharmacokinetic interaction.
Safety and efficacy of DepoDur when used in conjunction with therapeutic epidural doses of lidocaine with epinephrine (for conduction anesthesia) have not been studied in clinical trials.
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OVERDOSAGE
Overdosage of morphine is characterized by respiratory depression, with or without concomitant CNS depression. In severe overdosage, apnea, circulatory collapse, cardiac arrest and death may occur. The conditions that might cause an overdosage situation may vary from patient to patient. A DepoDur dose that is within the labeled dosing guidelines may be found to be more than could be tolerated by an individual patient. During post-marketing experience, spontaneous cases of apnea, respiratory arrest, and cardiac arrest have been reported after administration of labeled DepoDur doses (see WARNINGS and ADVERSE EVENTS). Since respiratory arrest may result either through direct depression of the respiratory center or as the result of hypoxia, attention should primarily be given to the establishment of adequate respiratory exchange through provision of a patent airway and institution of assisted or controlled ventilation. Opiates administered in addition to DepoDur to manage pain may precipitate or worsen adverse events such as respiratory depression. Additional opiates should be administered with caution.
The opiate antagonist, naloxone, is a specific antidote. An initial dose of 0.4 to 2 mg of naloxone should be administered intravenously, simultaneously with respiratory resuscitation. If the desired degree of counteraction and improvement in respiratory function is not obtained, naloxone may be repeated at 2- to 3-minute intervals. If no response is observed after 10 mg of naloxone has been administered, the diagnosis of opiate-induced, or partial opiate-induced, toxicity should be questioned. Intramuscular or subcutaneous administration may be used if the intravenous route is not available.
As the duration of effect of naloxone is considerably shorter than that of DepoDur, repeated administration or continuous infusion of naloxone may be necessary. Patients should be closely observed for evidence of recurrence of respiratory depression.
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CONTRAINDICATIONS
DepoDur is contraindicated in patients with known hypersensitivity to morphine, morphine salts, or any components of the product. DepoDur, as with all opiates, is contraindicated in patients with respiratory depression, acute or severe bronchial asthma, and upper airway obstruction. Any contraindications for an epidural injection preclude the administration of DepoDur. DepoDur, as with all opiates, is contraindicated in any patient who has or is suspected of having paralytic ileus. DepoDur should not be used in patients with suspected or known head injury or increased intracranial pressure.
DepoDur is an opiate analgesic which causes vasodilatation that may exacerbate hypotension and hypoperfusion and, therefore, is contraindicated in circulatory shock.
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DRUG ABUSE AND DEPENDENCE
DepoDur is a μ-agonist opiate and is a Schedule II controlled substance. Morphine, as with other opiates used in analgesia, can be abused and is subject to criminal diversion. Drug addiction is characterized by compulsive use, use for non-medical purposes, and continued use despite harm or risk of harm.
As with all potent μ-agonist opiates, tolerance as well as psychological and physical dependence to morphine may develop irrespective of the route of administration (intravenous, intramuscular, intrathecal, epidural or oral). Tolerance is a condition in which previous exposure to an opiate results in the necessity for increasingly larger doses of the drug in order to produce the same degree of analgesia. Withdrawal symptoms, indicating the presence of psychophysiological dependence, may occur when morphine is discontinued abruptly after chronic administration for analgesia, or upon administration of a drug with full or partial opiate antagonist effects. Care must be taken to avert withdrawal in patients who have been maintained on parenteral/oral opiates prior to epidural administration of DepoDur.
Individuals with a history of opiate or other substance abuse would be considered to be at greater risk of addiction or abuse, given that they are more apt to respond to the euphorigenic and reinforcing properties of morphine. However, concerns about abuse, addiction or diversion of opiates should not prevent proper management of pain.
DepoDur is intended for epidural use only. Abuse of DepoDur may pose a hazard of overdose and death when administered through other routes. This risk is increased with concurrent use of other medications or illicit drugs.
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